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The extinction of the Tasmanian tiger from the Australian mainland may have been driven by its inability to kill large prey, which placed it in direct competition with the dingo for food, new research shows.

An Australian team, led by University of New South Wales palaeontologist Dr Stephen Wroe, has found that although the Tasmanian tiger had a more powerful and efficient bite, its skull anatomy meant it was restricted to eating smaller prey.

The finding, published in today's Proceedings of the Royal Society B, is based on computer simulations of the bite forces and stress patterns placed on dingo and Tasmanian tiger skulls when biting struggling prey.

Co-author Colin McHenry, of the University of Newcastle, says the analysis helps clarify the basis for ecological competition between the larger Tasmanian tiger, or the thylacine, and the dingo.

"We would have thought the size of the predator's body would correlate to the size of the prey, but body size alone is not telling us the whole story," he says.

"There's much more of an overlap with the dingo in terms of prey."

The thylacine was a striped, dog-like carnivorous marsupial that was driven to extinction on mainland Australia about 3000 years ago.

Its demise has been linked to the arrival of the dingo, about 4000 years ago, in combination with climate change and a shift in Aboriginal land-use patterns.

The thylacine continued to survive on the southern island state of Tasmania, which was free of dingoes, until the arrival of European settlers, who hunted it down. The last thylacine, called Benjamin, died in a Tasmanian zoo in 1936.

Sophisticated

McHenry says in regions with large numbers of predators, such as Africa, there is little overlapping of prey, allowing animals to ecologically co-exist.

But the introduction of the dingo to Australia meant the thylacine was suddenly competing with a more "sophisticated predator", that also hunted in packs, for the same food.

"History would support the view there wasn't room for both types of predators," he says.

Stresses and strains

The researchers used to computer technology to model mechanical stresses and strains applying to the skull, jaw, teeth and cranial muscles of both animals.

They studied a range of biting, tearing and shaking motions that simulated the impact of controlling and killing a struggling prey.

Engineers use this same technique, known as finite element analysis, to test load-bearing materials such as plane wings and cars for possible distortion and failure.

"At one level we found the skulls were very similar," says McHenry. "But we also found these differences that seem to be saying the thylacine wasn't brilliant at tackling large prey the way the dingo was."

These differences were in the lower jaw and brain-case region of the skull.